wtf you guys. I can't believe you're talking about blacklisting these coins, as if that would be a good thing. No.
That would be one giant leap toward the traditional banking cartel. When you receive payment for something, do you want to have to check to see if any of those bits you got were from these stolen coins (or the thousands of others)? Were they within a couple transactions of these coins? Comb the entire transaction history to make sure they are not blacklisted somewhere? That sounds like a huge burden. Are you going to pay to have someone else do that for you? Those are the only 2 choices.
You want every coin to have special rules attached to it? Oh, this coin can't go to Bitstamp, and that one can't go to XXXX. That makes some coins worth more than others, and it means you're taking a risk every time you buy coins which you can't verify the history of. Fungibility is one of the key properties of bitcoin that make it better than the alternatives. You should not throw it away to maybe make this one guy's life more difficult.
Yeah, it sucks that these coins were stolen, and it's looking like the person who perpetrated the act may in fact be a bad guy. But it's time to shift the paradigm folks. These coins were stolen because it was possible to steal them. Bitstamp made that possible. Traditional money services have high fees to cover this shit, and bitcoin has low fees because it's secure, and you don't need to cover this shit if you're transacting properly. If you do something dumb, it's on you, we're not charging the consumers for the mistakes and inefficiencies of the money transmitters anymore. That's the point of bitcoin.
Bitstamp is in the process of rewriting their entire system from the ground up, to prevent this sort of thing happening again. Can you imagine Visa doing this after the Target hack? No, they keep doing the same thing, because you guys keep paying for their losses. There's no point in them changing anything. Bitstamp had suck ass security, a hacker fined them 5 million dollars for it. Their security (supposedly) will improve as a result. Gox died as a result, and we'd all have been better off if it happened way sooner than it did. Incompetence is not an option in this space, unless you have a shit ton of money to burn.
I agree with you that tainting "shouldn't be done". But in fact we see here a major bug in the bitcoin system: the PSEUDO anonymity. In a system based upon trustlessness, which is the FUNDAMENTAL axiom of bitcoin, namely that nobody has to trust anybody, the very fact that tainting is a physical possibility and hence that fungibility *doesn't really exist* (which comes down to the pseudo in pseudo anonymity), and that one should impose a rule that one should trust others not to blacklist coins, is a fundamental problem.
Even gold is more fungible than bitcoin then: you can melt gold and (unless for very special markers such as radioactive tracers) nobody can distinguish this gold from that gold.
I think that "mixing" like with Darkcoin (although that system is far from perfect too, as it requires trust to the mixing nodes) should somehow be implemented in bitcoin if that is still possible.